(20) Antiviral Immunity Flashcards
Are both innate and adaptive immunity important for blocking infection and eliminating virally infected cells?
yes
- What type of cytokines are released in innate immunity to fight viruses?
- What cells kill the infected cells in innate immunity? directly or indirectly?
- What can b cells do to fight viruses?
- What about T cells?
- type 1 interferon
- NK cells; either (indirect uses antibodies)
- Release antibodies that neutralize the virus
- Tc cells recognize viral epitopes and kill the infected cell
(Anti-Viral Immune Processes)
- Adaptive immunity is mediated by what? which do what?
- Antibodies allow what
- mediated by antibodies which block virus binding and entry into host cells
- ADCC by NK cells, and by Tc which eliminate infected cells
(Anti-Viral Immune Processes)
- Innate immunity does what three things?
- What are five means by which it fights viruses?
- inhibits virus processes, kills infected cells, and activates leukocytes
- complement, interferons, NK cells, Cytokines and chemokines, defensins
What do Tc cells secrete to block viral replication?
IFN-y
1-4. What do Tc cells release to kill virally infected cells?
- Is lysis of virus-infected cells always the answer?
- perforin - pore
- granzymes - serine proteases
- granulysin - induce apoptosis
- lymphotoxin (LT-a) - apoptosis
- NO!
- What is one way the viruses interfere with immune responses?
- by blocking MHC type 1 expression
- What do viruses interfere with to promote viral replication?
- What are some anti-apoptosis actions?
- Why would virus want to keep a cell alive?
- apoptosis
- block MHC 1 presentation, inactivate granzymes, prevent capase activation, production of virokines tha inhibit Tc function
- needs to use it to replicate
(Ab-dependent cellular cytotoxicity) (ADCC)
- Once a virus is intracellular - is it directly accessible to antibodies?
- but many viruses will insert their proteins into the cell membrane as they prepare to bud out of the cell
- what does this allow Ab to do? then what happens?
4. What is the main anti-viral activity of NK cells?
- no
- -
- Ab can attach to infected host cells; NK cells and macrophages bind and kill the cell
4. secretion of cytokines IFN-a/b and THF-a that activate other cells (not cell lysis!)
Are there viral mechanisms for evading NK cells?
Do we need to know them?
yes
it really doesn’t seem that way
1-3. What are the three things that antibodies do the fight viruses (humoral anti-viral immunity)?
- So how to B cells get activated?
- neturalization
- opsonization
- complement activation
- debris is picked up b dendritic cells (for example) - then go to draining lymph nodes and present to B cells
- opsonization can be used for what two things?
- phagocytosis or activation of NK cells
(Ab and Viral Immunity)
viruses evade by antigenic shift
- evasion also occurs by the shedding of what from the viral capside protein?
- or inclusion of viral proteins in the capside thatn blcock what?
- other viral proteins may disrupt the complement cascade
- shedding of antigen
- complement-mediated lysis
- Pro-inflammatory property of complement assists with what?
- Cleavage products from complement proteins act on blood vessels to increase what?
- This is especially important for viral clearance in that what?
- In addition virus infected cells can by lysed by what if what?
- What else assists in virus-infected cells uptake and degradation by phagocytes?
- viral clearance
- vascular permeability
3. IgG, IgM, and Tc cells can extravasate to sites of inflammation
- by complement if antibodies are bound to the cell surface
- opsonization of virus-infected cells or particles
- Do viruses have ways of inhibiting complement?
- what messes with binding of antibody to C1?
- what messes with c3/c5 convertase
*they mess up a lot of complement stuff
* he wants us to remember that complement deals with more than anti-bacterial (anti-viral too!)
- yes
- influenza
- herpes